The present invention relates to sealing arrangements for establishing sealing barriers for rotors extending from an oil-immersed region to an air-immersed region, and more particularly, to a face seal system which incorporates an oil weep drain, secondary seals, and buffer systems into a housing and is operative to shorten the xe2x80x9ceffectivexe2x80x9d length of the sealing system, thereby reducing rotor length and weight.
Air exhaust from turbo-machinery is often released into areas populated by people. Oil, which can leak into this air due to the high pressures, high temperatures, and/or high speeds, under which the turbo-machinery operates, results in an unpleasant smell and sometimes produces smoke to which the people are exposed. This has become a major cause of removal and/or excessive maintenance of propulsion engines and auxiliary power units (APUs).
The prior art is replete with sealing apparatus for minimizing passage of fluids across barriers. Some of the apparatus focus on using a multiplicity of seals (see U.S. Pat. No. 3,085,808 to Williams, U.S. Pat. No. 4,619,364 to Mitumaru, and U.S. Pat. No. 3,360,272 to Blom et al.), while others focus on maintaining pressure control (see U.S. Pat. No. 3,813,103 to Wiese, U.S. Pat. No. 3,926,442 to Muller, and U.S. Pat. No. 4,087,097 to Hossens et al.), but none incorporate provisions for controlling the axial length of the sealing system, nor is there any concern for the resulting weight increase due to the increased length of the turbo-machinery.
A more recent solution developed by the assignee of the present invention includes a system for oiled sumps which uses a carbon ring seal (primary air-to-oil seal), two oil xe2x80x9cweepxe2x80x9d drains, secondary air-to-oil seals, and a single air buffer system in conjunction with the stationary housing of the turbo-machinery. This arrangement has proven to be effective in significantly reducing, if not nearly eliminating, oil leakage. However, when used with a carbon face seal, the axial length of the improved system is increased an extensive and unacceptable amount with a corresponding increase in engine weight, and a negative impact on the dynamics of the rotor system.
Therefore, there exists a need for sealing apparatus using a face seal to keep lubricating oil on one side of turbo-machinery, such as a gas turbine engine, from passing to the air, or compressor, side of the turbo-machinery which will contribute to reduction of the effective overall axial length of the sealing system, achievement of a meaningful reduction of weight in the turbo-machinery, and also improvement of the system""s dynamic characteristics.
In one aspect of the present invention, a sealing apparatus comprises a housing including a portion for retaining the face seal element and a biasing element for urging the face seal element into sealing engagement with a portion of the rotor of the turbo-machinery, and further comprises an axial extending leg portion which defines, with the portion for retaining the face seal element, a fluid flow path through the housing for removing oil which has breached the face seal element-rotor interface.
In another aspect of the invention, variations of the structure of the seal housing are disclosed which provide the same oil-air isolation function but which operate with potentially greater efficiencies.
Other aspects, advantages and features of the invention will become more apparent and better understood, as will equivalent structures, which are intended to be covered herein, with the teaching of the principles of the invention in connection with the disclosure of the preferred embodiments thereof in the specification, claims and drawings.